Polish Prime Minister Donald Tusk said the country’s airspace was “violated by a huge number of Russian drones” on Tuesday night and any drones that “posed a direct threat” were shot down. The incident marks the first time a NATO member has opened fire during the Ukraine war.[time-brightcove not-tgx=”true”]Speaking to the Polish parliament on Wednesday, Tusk said that in light of the overnight incidents, the possibility of a large conflict was “closer than at any time since World War II.”“There is no reason to claim that we are in a state of war… but the situation is significantly more dangerous than all previous ones,” Tusk determined.Detailing the incident, Tusk reported that 19 drones had violated Polish airspace as Russia continues launching airstrikes on the country’s neighbour Ukraine. In response to Poland’s allegations, Russian Charge d’Affaires Andrei Ordash told Russian state media Ria Novosti that he had been summoned by the Polish Foreign Ministry and that Warsaw provided no evidence of the drones being of Russian origin.The Russian Ministry of Defense also said that there were “no targets planned for destruction on Polish territory,” in an update published on Telegram on Wednesday.“The maximum flight range of the Russian UAVs used in the strike, which allegedly crossed the border with Poland, does not exceed 700 km. Nevertheless, we are ready to hold consultations with the Polish Ministry of Defense on this topic,” read the Ministry’s statement.TIME has reached out to Russia’s Ministry of Defense for further comment.Read More: Russia Issues Stern Response to Trump’s Sanctions ThreatTusk said he had asked NATO to open consultations under Article 4 of the alliance’s treaty. Under Article 4, NATO members can raise an issue with other members and “the Parties will consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened.”“Last night, numerous drones from Russia violated Polish airspace,” NATO Secretary General Mark Rutte told reporters at a briefing on Wednesday, adding that air defense systems successfully “ensured the defense of NATO territory.”Rutte said that a number of countries were involved in the operational response alongside Polish F-16 jets, including military equipment from Italy, Germany, and the Netherlands.Rutte expressed solidarity to Poland on behalf of NATO and its allies, and denounced Russia.“A full assessment of the incident is ongoing. What is clear is that the violation last night is not an isolated incident,” he said. “Allies are resolved to defend every inch of allied territory… This only reinforces the importance of NATO and the path to which allies agreed at our summit in the Hague earlier this year. We need to invest more in our defense, ramp up defense production so that we have what we need to deter and defend.”Rutte spoke of Russia’s attacks against Ukraine following its invasion of the country in 2022, saying: “Russia is waging a dangerous war of aggression against Ukraine that continuously targets civilians and civilian infrastructure.”A number of Ukrainian allies and European leaders have condemned the presence of drones in Poland. E.U. High Representative Kaja Kallas called it “the most serious European airspace violation by Russia since the war began.”Ukrainian President Volodymyr Zelensky said that his forces were informing Poland of movement from Russian drones. “In total, at least several dozen Russian drones were moving along the border of Ukraine and Belarus and across western regions of Ukraine, approaching targets on Ukrainian territory and, apparently, on Polish territory,” he said, adding that Ukraine is ready to expand its cooperation with allies on information sharing and aerial defenses.Read More: Zelensky Hails ‘America’s Readiness to Provide Support to Ukraine’ as World Leaders Map Out Security GuaranteesU.K. Prime Minister Sir Keir Starmer called the incident in Poland “egregious and barbaric.”“With our partners—and through our leadership from the Coalition of the Willing—we will continue to ramp up the pressure on Putin until there is a just and lasting peace,” he vowed.During a Coalition of the Willing meeting in Paris last week, 26 countries committed to deploying troops in Ukraine to serve as a “reassurance force” once the conflict with Russia ends.